Your photos from the Jupiter seems pretty sharp to me.
I think why you feel it's not "sharp" is cause of the different rendition of contrast and colors.
The sonnar design is some what sharp yet soft. Makes it more pleasing. Doesn't have that over contrasty and over sharpened rendition that makes most photos look so digital. If you're looking for pixel sharpness, the sonnar design is not one to go after, even if it's the $1600 Zeiss ZM version, the look will be similar . But I find that it has one more the best color and OOF renditions, dreamy smooth some what muted.
I don't like the Planars, they are too contrasty and "sharp". It's a good/great lens, but different character which I'm not interested in.
Value wise, the Jupiter is hard to beat.
Thanks Bro, your insights has made me look at the Jupiter 3 differently and appreciate its strength more instead of the cookie cutter lens attributes =D. I saw bro Drawde wedding pictures taken on his Jupiter, really nice.